Hydraulic motor of the wobble plate type



Aug. 9,1949; R; c. GRIFFITH 2,478,481

HYDRAULIC MOTOR OF THE WOBBLE PLATE TYPE Filed Maroh'22, 1945 Patented Aug. 9, 1949 HYDRAULIC MOTOR OF THE-'WGBBLE'" PLATE TYPE' Raymond 'CL'Griflith, Columbus, Ohio AppliatifimMa'rchQZ, 1945, Serial N0."584,062

ICIaimF (Cl. 12162) draulic motor of the wobble plate type;- wherein. the wobble plate is automaticallyiadjusted in response to changes of load: so as to'increase the torque developed by themotor-zwhenever the:

load increases and to decrease thetorque de-'- veloped by themotor whenever the load decreases.

Another object of thisrinvention is to 1 provide a hydraulic motorthat may, be reversed, which hydraulic motor? stores renergyrxduring. the period of time'that the rotation oft-the motor is: coming to a stop, which stored energyiiszreleasedr to the motor immediately after it. has reversed:

Another object of this invention is-to provide.

a substantially constant power 7 output umctor.

Another object of. this inventionisztosprovide'.

a fluid pressure responsive device for controlling the angular relation of a:-wobble plateiwith re--- spect to the pistons,to-Vtherebycontrolthe torque developed by the motor in proportion .tothe load.

apparent from" the following 7 descriptiom In the drawing, Figure iisea cross sectionalw view of the motor to show the arrangement-oi the wobble plate and the adjusting mechanism.

therefor taken substantially :n-the.line .-l-l of Figure 2. g 7

Figure 2 is another cross sectional view=showing the valve control mechanisnnusedl in revers-.- ing the motor, taken-substantially; on .the'line- 2.2 of Figure l. a 7

Figure 3 is a fragmentary, view- 0f the base,

taken substantially on the line-3? of Figure 2.

The device disclosed herein-is provided with Other objects and advantageszreside in the construction of par-ts,-- the-combination thereof and the mode of operation, as will become more 2- tached'to one end 'ofa housing '12 having rotat= ably"mounted therein a piston-carrying .rctor I4 and a cylindrical cavity 16. The rotor I4 iszproe vided with a plurality of cylindrical recesses 18:" Each cylindrical recess w has mounted therein a piston 2i} urged upwardly by asuitable spring '22. The upper ends of the pistons-Mare curved at 24 and engage a race 260i a bearingmounted: in a wobble plate 28; The wobble plate28i as best seen in Figure 2; is pivotally'mountedat 30 on pintles 32 mounted-in the sides 'of the housing !2.- The Wobble -pl'ate' 28-is' provided. with a shank 'or lever 36 provided with-a trans.-: verse pin 38,-the upper end of 'whichis seated against a disc-shaped member 40 urged down: wardly by a spring 42, havingthe upper'en'd seated in a suitable recess in a capping'member 440ithe housing 12." The lower end of the-pin: 38 is. seated on top of a -pi'ston 46 -mounted in: the cylindrical cavity 16. I

A drive shaft 59 has one end splined in' the rotor 14 and journall'ed in-a suitablebearing in the capping member 44 of the--housing,'l2." The rotor is hydraulically driven; as is 'well known to those skilled'in the art'of the wobble-'- plate type of motor. Thehydraulic fluidis-sup-" plied from a suitable source through a gear pump? including the gears 52 and 54; Thegear 52*is' driven through a shaft '56 from a suitable sourceof power, which gear52in turn drives thegear 54 mounted upon the stubshaft 58. The fluid is discharged through a suitable passage or -conduit" 60 shown in dotted lines in Figure *1; commurii eating with a passage or'con'duit't2 als'o shown" 352m dotted lines, intersecting a transverse passage an energystorage cylinder provided withta piston i 7 operating against a spring, such that as the. .pressure in the fluid Tline increases-the piston is V actuated against the spring to increase the angle power output, even though'tthe load-changes from no load to-full loadl Referring to the drawing, atfluid passagebase Thea energy storing.

or conduit 64 and a verticalpassage'oncondtiit 66 communicating with the cylindrical cavity I69 The base 10 isfprovided' withapairof-semicircular recesses 10 and112. The recess' 10 communicates with the end: 64a of"'the passage' t i and the recess 12 com'municateswiththe-pas sage 64, as clearly shown in Figure 2. The=semi circular recess 10 registers with half of thecylin drical cavities inthe rotor l4- and the semicircular recess 12 communicates.With the-Other half of the cylindricaltcavitiesv in therotor I45 A valve member 80,. controlled by an electric' magnet or solenoid 82, when inithefull'lin'e posi tion shown in Figure 2, .causes the fluid to vcir "culate from the passage 62 through 'aLportiori of the passage 64 through the semi-circular recess 12 to one-half of the cylindrical cavities in the rotor [4,-so aslto exert pressurelon the plstonsin the cylindrical cavitieswof:one-ehalilotthe rotor?- 10,1also forming a .valve support, is fixedly; at-- "As-the-pistons exert.a=pressureaupwardly against the wobble plate 28, the pistons rotate the rotor. When this takes place, the fluid in the other half of the pistons is exhausted through the semicircular recess through the end portion 84a of the passage beyond the electromagnetic valve 80, where the fluid is discharged around the rotor through the cavity 84, where it returns to the gear pump. This causes the rotor l4 and the shaft 50 to rotate in one direction. By operating the electric magnet 82 from the full line position shown in Figure 2 to the dotted position shown in the same figure, the hydraulic fluid is supplied under pressure to the semi-circular recess 10 and the recess 12 functions as an exhaust. This causes the rotor to reverse.

The operation of this hydraulic motor, with the exception of the reversing mechanism, is similar to conventional hydraulic motors of the multiple piston type. If the rotor is operating at a high speed, it can readily be seen that a reversal of the flow of the fluid through the rotor by actuating the electromagnetic valve 80 would cause a terrific jar and pounding in the motor. Furthermore, if the wobble plate remains at the same angular position, the speed of the rotor will be influenced by the load.

In order to overcome some of these objections, a speed control mechanism has been provided. In addition to the control of the speed, this mechanism functions as a cushioning member for absorbing the shock when reversing the motor and it also functions to store up energy caused by the reversal of the motor, which energy is liberated as soon as the rotor reverses its direction to rapidly accelerate the operation of the rotor.

The speed control mechanism and load control mechanism includes the shank 36 that oscillates the wobble plate 28, the disc-shaped member 40, the spring 42 and the piston 46. The fluid under pressure passes through the passage 62. and the passage 66 into the cylindrical cavity l6. As the,

load increases on the rotor Hi, the pressure builds up in the hydraulic system, so as to raise the piston 46 and thereby increase the angle of the Wobble plate 28, so that the rotor develops more torque and tends to decelerate. The piston 46 is then shown in the near up position. If the piston is raised higher, the fluid escapes through a vent 90', thereby limiting the upward movement of the piston 46. When the load on the rotor decreases, the pressure in the hydraulic system decreases, permitting the piston 46 to move downwardly, thereby decreasing the angle of the wobble plate 28 so as to increase the speed of the rotor, as is well known to those skilled in the art. 7

When the electromagnet 82 moves from one position to another so as to actuate the valve member 80 from one position to another, the pressure in the hydraulic system increases very rapidly, thereby causing the piston 46 to raise. As the piston 46 is raised, the angle of the wobble plate 28 is increased, thereby increasing the torque generated by the pistons. This will result in a very rapid acceleration of the rotor when it is reversed. As the pressure in the system decreases, resulting from the acceleration of the rotor, the spring 42 forces the piston downwardly and as the piston and the spring advance downcontrol to maintain the rotor at a substantially constant power, irrespective of the load.

An electromagnet has been shown here as illustrative of a valve control mechanism for actuating the valve. This valve may be actuated in any other suitable manner, either driven directly or indirectly from the prime mover or from any other source of power, or it may be manually controlled. For some usages of the 'motor the valve may be actuated periodically from one position to another, so as to cause the motor to reverse cyclically, for example, if the motor is used in actuating a washing machine where it is desirable to reverse the direction of movement, a suitable .control mechanism may be provided for the valve actuating mechanism such that the motor reverses periodically.

Whenever this motor is used as a reversible motor, asfor example, when it is used as a washing machine motor, and whenever the motor is reversed for any other reason, the inertia of the movable parts connected to the rotor of the motor tends to continue the rotation of the rotor. Whenever the valve so is reversed and the motor is in rotation, the rotor functions as a hydraulicpump from the time the valve is reversed until the rotor stops. The only place that the hydraulic fluid can escape is to the power control piston 46. As soon as the rotor comes to a stop, it ceases to pump fluid and instead, receives fluid. Immediately after the rotor has come to a stop, fluid is supplied to the rotor from the gear pump and also from the piston 36 actuated by the spring 42, which has stored up energy and now delivers this energy to the rotor. Thus, it can be seen that the rotor will have a tremendous amount of power delivered to it, causing the rotor to accelerate at a very rapid rate. This is very desirable when the motor is used as a Washing machine Lmotor. When it is used as a washing machine motor, power is delivered to the rotor from two sources, the gear pump and the piston 46. As soon as the pressure decreases, the angle of the wobble plate is decreased, thereby further tending to accelerate the motor.

Instead of the cylinder l5 and. the piston 45 acting against the spring 42, any other pressure responsive device could be used, as for example, a bellows moving in response to changes in pressure. V V

Although the preferred embodiment of, the device has been described, it will be understood V defined in the appended claim.

wardly, the angle of the wobble plate 28 is de- 46 is such that when the proper speed is attained,

the spring and the piston function as a power Having thus described my invention, I claim:

In a reversible hydraulic motor of the wobble plate type, said motor including a frame, having a cylindrical cavity, a rotorassembly mounted in the cylindrical cavity, said rotor assembly including a plurality of pistons, an adjustably,

mounted wobble plate pivotally mounted in said frame, said wobble plate being provided with a laterally disposed arm, said frame member being provided witha second cylindrical cavity extending parallel to the first cylindrical cavity but ar ranged in offset relation, therefrom, a piston fluid to the pistons in the rotorgsaid passagemember being attached to the frame member,

S said passage member having a passage communicating with the said second cylindrical cavity, a capping member for the frame member, said capping member being provided with a bearing, a rotor shaft attached'to the rotor journalled in said bearing, said capping member having a cylindrical recess, a compression spring having one end seated in said cylindrical recess, and a disclike member being provided with a cylindrical recess in which the other end of the compression spring is seated, said disc-like member engaging one side of the arm of the wobble plate, the opposite side of the arm resting upon said piston, said compression spring biasing said arm of the wobble plate so that the wobble plate approaches a plane substantially normal to the axis of rotation of the rotor, said piston in the cylinder actuating said arm against the compression spring so as to cause the wobble plate to form an in clined angle with respect to the axis of rotation a of the rotor as the pressure in the system increases due to an increase in load, the compression spring tending to urge the piston into the cylindrical cavity whenever the pressure in the hydraulic system decreases.

RAYMOND C. GRIFFITH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re.2 ,'758 Foisy a a ..fl Apr. 1, 1941 1,165,825 Wood Dec. 28, 1915 1,273,618 Julien et al. July 23, 1918 1,624,151 Shevlin Apr. 12, 1927 1,734,816 Ludwig Nov. 5, 1929 1,840,866 Rayburn et a1; Jan. 12, 1932 2,129,886 Syrovy Sept. 13, 1938 2,299,233 Hofier Oct. 20, 1942 2,392,980 Fawkes Jan. 15, 1946 FOREIGN PATENTS Number Country Date 10,108 Great Britain Apr. 28, 1909 181,565 Great Britain June 22, 1922 303,215 Great Britain Jan. 3, 1929 

